The top three Democratic presidential contenders remain locked in a close battle in Iowa, with Sen. Hillary Rodham Clinton (N.Y.) seeing her advantages diminish on key issues, including the questions of experience and which candidate is best prepared to handle the war in Iraq, according to a new Washington Post-ABC News Poll.

Sen. Barack Obama (Ill.) draws support from 30 percent of likely Democratic caucus-goers in Iowa, compared with 26 percent for Clinton and 22 percent for former senator John Edwards (N.C.). New Mexico Gov. Bill Richardson received 11 percent. The results are only marginally different from a Post-ABC poll in late July, but in a state likely to set the tone for the rest of the nominating process, there are significant signs of progress for Obama -- and harbingers of concern for Clinton.

The factors that have made Clinton the clear national front-runner -- including her overwhelming leads on the issues of the Iraq war and health care, a widespread sense that she is the Democrats' most electable candidate, and her strong support among women -- do not appear to be translating on the ground in Iowa, where campaigning is already fierce and television ads have been running for months.

At the heart of the Democratic race has been the dichotomy between strength and experience (qualities emphasized by Clinton, Richardson, and Sens. Joseph R. Biden Jr. of Delaware and Christopher J. Dodd of Connecticut in their appeals) and the ability to introduce a new approach to governing (as Obama and Edwards have promised to do).

Iowa Democrats are tilting toward change, and Obama appears to be benefiting from it.

Fifty-five percent of those surveyed reported that a "new direction and new ideas" are their top priority, compared with 33 percent who favored "strength and experience." That is a shift from July, when 49 percent sought change and 39 percent experience.

Nationally, Clinton is viewed as a candidate of change, with support from 41 percent of Democrats seeking a new direction in a recent Post-ABC poll. But in Iowa, Obama dominates the "change" vote, winning 43 percent of that group, compared with 25 percent for Edwards and 17 percent for Clinton.

Still, Clinton retains a comfortable lead among Iowa voters who consider strength and experience more important. She is supported by 38 percent of Democrats, compared with 19 percent for Edwards, 18 percent for Richardson and 12 percent for Obama, according to the new survey.

She appears more vulnerable on questions of character. Thirty-one percent found Obama to be the most honest and trustworthy, about double the percentage who said the same of Clinton. While about three-quarters credited both Obama and Edwards with speaking their mind on issues, only 50 percent said Clinton is willing enough to say what she really thinks. Forty-five percent said she is not sufficiently candid.

Overall, the poll points to some strategic gains for Obama. His support is up eight percentage points since July among voters 45 and older -- who accounted for two-thirds of Iowa caucus-goers in 2004. He also runs evenly with Clinton among women in Iowa, drawing 32 percent to her 31 percent, despite the fact that her campaign has built its effort around attracting female voters.

And despite widespread impressions that Obama is banking on unreliable first-time voters, Clinton depends on them heavily as well: About half of her supporters said they have never attended a caucus. Forty-three percent of Obama's backers and 24 percent of Edwards's would be first-time caucus-goers. Previous attendance is one of the strongest indicators of who will vote.

Clinton's reliance on new voters helps explain her campaign's recent push to drive up attendance on caucus night -- including a new "caucusing is easy" video featuring former president Bill Clinton and a hamburger -- and also illustrates why Edwards, with his cadre of experienced caucus-goers, remains a formidable threat.

In another positive shift for Obama, 55 percent now see him as their first or second choice, an important trend in a state where a person's second choice can matter and voters often switch their support at the last minute.

According to Democratic Party rules, candidates must draw at least 15 percent at each caucus site for the votes to count; if that fails to happen, their supporters often throw their votes to a more viable contender. In this poll, 34 percent of those voters would make Obama their second choice, 28 percent Edwards and 15 percent Clinton.

Most supporters of the three front-runners said they will "definitely" support their chosen candidate on Jan. 3. About two in 10 said there is a "good chance" that they will change their minds. That level of certainty suggests the race will continue to be close in the weeks ahead.

Voters in Iowa continue to view Clinton as the most viable of the Democrats, although her advantage is significantly smaller than it is nationally. About four in 10 Iowa voters called her the Democrats' best hope for November 2008, a quarter said it is Obama, and 22 percent said Edwards. In the latest Post-ABC national poll, 62 percent said Clinton is the party's strongest general-election candidate.

The results of the survey, conducted Nov. 14 to 18, underscore the urgency and fluidity of the contest as it heads into its final seven-week stretch. The poll was conducted by telephone among a random sample of 500 Iowa adults likely to vote in the 2008 Democratic presidential caucus; the results have a margin of sampling error of plus or minus four percentage points.

Iraq and health care dominate as the campaign's top issues. A third of likely voters described the war as the biggest issue in their choice for the nominee, while 26 percent said it is health care. Ten percent highlighted the economy and jobs, and all other issues were in the single digits.

The race at the local level only somewhat resembles the national campaign. While Clinton held a 51-point lead on the question of which Democrat would best handle the issue of health care in a national Post-ABC poll in late September, she now has a narrow nine-point advantage on that question in Iowa.

And Clinton does not have a meaningful edge on the five other issues in this poll. She runs about even with Obama as the candidate most trusted to handle the economy, Social Security and the situation with Iran. On dealing with the war in Iraq, Clinton's 12-point lead from July has evaporated. In the new poll, 26 percent most trust Obama on Iraq and 23 percent choose Clinton, with 15 percent each for Edwards and Richardson.

Richardson, the only Hispanic candidate, came in fourth on many questions. But on the explosive matter of immigration, 25 percent said they trust him the most. During the Democratic candidates' last debate, Richardson gave a clear answer to the question of whether he would give driver's licenses to illegal immigrants, saying that as governor he already had. The same question has flummoxed Clinton and Obama at various points.

Among all voters surveyed, 38 percent said Clinton has the best experience to be president, ahead of her rivals but lower than in July, when 50 percent said so.

Regardless of whom they support, voters reported being deeply involved in -- or at least bombarded by -- the campaign. More than half said they had already attended a campaign event. More than four in 10 had visited a candidate's Web site; two in 10 had donated money. Eight in 10 reported receiving calls from one or more of the campaigns; 38 percent have been e-mailed.

And in a sign of just how personal Iowa politics are, a third said they have spoken to or shaken hands with one or more of the candidates. Two in 10 have met one of the three leading Democrats; 3 percent have met all three.